Chris Stapleton brought a tear to listeners' eyes with his emotional performance at the 2021 ACM Awards in Nashville on Sunday night (April 18). The gravel-voiced country superstar gave a plaintive rendition of "Maggie's Song," which he wrote after losing his beloved dog.

In a surprise, Miranda Lambert showed up and sang gorgeous harmonies over the beautifully bittersweet tune. Stapleton's wife and frequent collaborator Morgane Stapleton was originally due to sing harmonies, but had to drop out due to a prior doula commitment.

Sitting in a circle in the famed Bluebird Cafe and surrounded by stacked stools, Stapleton and Lambert were in lockstep while singing a tribute to faithful furry friends. Given Lambert's lifelong love of dogs and her non-profit organization MuttNation, the last-minute collaboration fit like a glove.

"Maggie's Song" appears on Stapleton's most recent album, Starting Over. It chronicles his family's life with their dog Maggie, who died in 2019 at the age of 14. They originally found her abandoned in a shopping cart as a "fuzzy black pup," and the song ends on a universally poignant note as he recalls her final moments: "I told her she was a good dog / And I told her goodbye / Run, Maggie, run / With the heart of a rebel child / Run Maggie, run / Be just as free as you are wild," Stapleton sings.

“It’s all true stuff. There’s no embellishment in it,” Stapleton told the Los Angeles Times in November.

"That one was hard to sing. I kept crying through a lot of it," he added. "I'm no authority on masculinity, but I don't feel un-masculine or embarrassed by having feelings. In fact, I think it's the most manly thing you can do."

Stapleton held it together for the ACM performance, but that's more than most at home can probably say.

Stapleton went into the ACMs broadcast on Sunday night as a multiple nominee. He was nominated for Entertainer of the Year, and Starting Over received a nod for Album of the Year, while its title song was nominated for Song of the Year.

The 2021 ACM Awards air live on CBS and stream live on Paramount+. Sign up for Paramount+ here.

2021 ACM Awards Show Photos:

The 2021 ACM Awards took place in Nashville on Sunday night (April 18). Luke Bryan was crowned Entertainer of the Year, while Thomas Rhett and Maren Morris were named Male and Female Artist of the Year, respectively.

The three-hour show was also packed with performances from Miranda Lambert, Luke Combs, Little Big Town and many more. Artists were at the Grand Ole Opry House, the Ryman Auditorium and the Bluebird Cafe, as well as on Lower Broadway, at the Station Inn and along the Nashville riverfront.

Keith Urban and Mickey Guyton co-hosted the show.

See Pictures From the 2021 ACM Awards Red Carpet:

The best dressed on the 2021 ACM Awards red carpet brought color — lots of color — for an awards show that promises to be a celebration. Photos show stars like Carly Pearce, Kelsea Ballerini, Chris Young, Kane Brown and more wearing the hottest and often most expensive designer outfits, or suits they designed themselves, in the case of Jimmie Allen.

Check out a full gallery of country music's hottest stars on the ACM Awards red carpet. Who do you think is best dressed and worst dressed?

The 2021 ACM Awards took place at the Bluebird Cafe, Grand Ole Opry and Ryman Auditorium in Nashville on Sunday (April 18).